This patch has been mailed to upstream. No reply at this time. Status unknown.

--- a/libjbig/Makefile
+++ b/libjbig/Makefile
@@ -1,28 +1,58 @@
 # Unix makefile for the JBIG-KIT library
 
 # Select an ANSI/ISO C compiler here, GNU gcc is recommended
-CC = gcc
+AR ?= ar
+CC ?= gcc
+RANLIB ?= ranlib
 
 # Options for the compiler: A high optimization level is suggested
-CFLAGS = -g -O -W -Wall -ansi -pedantic # --coverage
+override CFLAGS += -W -Wall -ansi -pedantic # --coverage
 
-all: libjbig.a libjbig85.a tstcodec tstcodec85
+ifeq ($(shell uname),Darwin)
+	SONAME = dylib
+	LIBDIR ?= /usr/lib
+else
+	SONAME = so
+endif
+
+all: libjbig.$(SONAME) libjbig85.$(SONAME) tstcodec tstcodec85
+
+static: libjbig.a libjbig85.a
 
 tstcodec: tstcodec.o jbig.o jbig_ar.o
-	$(CC) $(CFLAGS) -o tstcodec tstcodec.o jbig.o jbig_ar.o
+	$(CC) $(LDFLAGS) $(CFLAGS) -o tstcodec tstcodec.o jbig.o jbig_ar.o
 
 tstcodec85: tstcodec85.o jbig85.o jbig_ar.o
-	$(CC) $(CFLAGS) -o tstcodec85 tstcodec85.o jbig85.o jbig_ar.o
+	$(CC) $(LDFLAGS) $(CFLAGS) -o tstcodec85 tstcodec85.o jbig85.o jbig_ar.o
 
 libjbig.a: jbig.o jbig_ar.o
 	rm -f libjbig.a
-	ar rc libjbig.a jbig.o jbig_ar.o
-	-ranlib libjbig.a
+	$(AR) rc libjbig.a jbig.o jbig_ar.o
+	-$(RANLIB) libjbig.a
+
+SOBJS = jbig.lo jbig_ar.lo
+
+libjbig.so: $(SOBJS)
+	$(CC) $(CFLAGS) -shared $(LDFLAGS) -o $@ -Wl,-soname -Wl,$@ $(SOBJS)
+
+libjbig.dylib: $(SOBJS)
+	$(CC) $(CFLAGS) -dynamic $(LDFLAGS) -o $@ -dynamiclib -install_name $(LIBDIR)/$@ $(SOBJS)
+
+SOBJS85 = jbig85.lo jbig_ar.lo
+
+libjbig85.so: $(SOBJS85)
+	$(CC) $(CFLAGS) -shared $(LDFLAGS) -o $@ -Wl,-soname -Wl,$@ $(SOBJS85)
+
+libjbig85.dylib: $(SOBJS85)
+	$(CC) $(CFLAGS) -dynamic $(LDFLAGS) -o $@ -dynamiclib -install_name $(LIBDIR)/$@ $(SOBJS85)
+
+%.lo: %.c jbig.h jbig85.h jbig_ar.h
+	$(CC) $(CFLAGS) -fPIC -c $< -o $@
 
 libjbig85.a: jbig85.o jbig_ar.o
 	rm -f libjbig85.a
-	ar rc libjbig85.a jbig85.o jbig_ar.o
-	-ranlib libjbig85.a
+	$(AR) rc libjbig85.a jbig85.o jbig_ar.o
+	-$(RANLIB) libjbig85.a
 
 jbig.o: jbig.c jbig.h jbig_ar.h
 jbig85.o: jbig85.c jbig85.h jbig_ar.h
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,10 @@
 # Unix makefile for JBIG-KIT
 
 # Select an ANSI/ISO C compiler here, GNU gcc is recommended
-CC = gcc
+CC ?= gcc
 
 # Options for the compiler: A high optimization level is suggested
-CFLAGS = -O2 -W -Wno-unused-result
+override CFLAGS += -W
 # CFLAGS = -O -g -W -Wall -Wno-unused-result -ansi -pedantic # -DDEBUG
 
 export CC CFLAGS
@@ -36,7 +36,7 @@
 distribution:
 	rm -rf jbigkit-$(VERSION)
 	git archive v$(VERSION) --prefix jbigkit-$(VERSION)/ | tar xvf -
-	make -C jbigkit-$(VERSION)/pbmtools txt
+	$(MAKE) -C jbigkit-$(VERSION)/pbmtools txt
 	tar cvaf jbigkit-$(VERSION).tar.gz jbigkit-$(VERSION)
 
 release:
--- a/pbmtools/Makefile
+++ b/pbmtools/Makefile
@@ -1,11 +1,11 @@
 # Unix makefile for the JBIG-KIT PBM tools
 
 # Select an ANSI/ISO C compiler here, e.g. GNU gcc is recommended
-CC = gcc
+CC ?= gcc
 
 # Options for the compiler
-CFLAGS = -g -O -W -Wall -Wno-unused-result -ansi -pedantic # --coverage
-CPPFLAGS = -I../libjbig 
+override CFLAGS += -W -Wall -Wno-unused-result -ansi -pedantic # --coverage
+override CPPFLAGS += -I../libjbig
 
 .SUFFIXES: .1 .5 .txt $(SUFFIXES)
 .PHONY: txt test test82 test85 clean
@@ -15,16 +15,16 @@
 txt: pbmtojbg.txt jbgtopbm.txt pbm.txt pgm.txt
 
 pbmtojbg: pbmtojbg.o ../libjbig/libjbig.a
-	$(CC) $(CFLAGS) -o pbmtojbg pbmtojbg.o -L../libjbig -ljbig
+	$(CC) $(LDFLAGS) $(CFLAGS) -o pbmtojbg pbmtojbg.o -L../libjbig -ljbig
 
 jbgtopbm: jbgtopbm.o ../libjbig/libjbig.a
-	$(CC) $(CFLAGS) -o jbgtopbm jbgtopbm.o -L../libjbig -ljbig
+	$(CC) $(LDFLAGS) $(CFLAGS) -o jbgtopbm jbgtopbm.o -L../libjbig -ljbig
 
 pbmtojbg85: pbmtojbg85.o ../libjbig/libjbig85.a
-	$(CC) $(CFLAGS) -o pbmtojbg85 pbmtojbg85.o -L../libjbig -ljbig85
+	$(CC) $(LDFLAGS) $(CFLAGS) -o pbmtojbg85 pbmtojbg85.o -L../libjbig -ljbig85
 
 jbgtopbm85: jbgtopbm85.o ../libjbig/libjbig85.a
-	$(CC) $(CFLAGS) -o jbgtopbm85 jbgtopbm85.o -L../libjbig -ljbig85
+	$(CC) $(LDFLAGS) $(CFLAGS) -o jbgtopbm85 jbgtopbm85.o -L../libjbig -ljbig85
 
 jbgtopbm.o: jbgtopbm.c ../libjbig/jbig.h
 pbmtojbg.o: pbmtojbg.c ../libjbig/jbig.h
@@ -33,11 +33,11 @@
 
 ../libjbig/libjbig.a: ../libjbig/jbig.c ../libjbig/jbig.h \
 	../libjbig/jbig_ar.c ../libjbig/jbig_ar.h
-	make -C ../libjbig libjbig.a
+	$(MAKE) -C ../libjbig libjbig.a
 
 ../libjbig/libjbig85.a: ../libjbig/jbig85.c ../libjbig/jbig85.h \
 	../libjbig/jbig_ar.c ../libjbig/jbig_ar.h
-	make -C ../libjbig libjbig85.a
+	$(MAKE) -C ../libjbig libjbig85.a
 
 analyze:
 	clang $(CPPFLAGS) --analyze *.c
@@ -45,22 +45,22 @@
 test: test82 test85
 
 test82: pbmtojbg jbgtopbm
-	make IMG=ccitt1     OPTIONSP=                      dotest1
-	make IMG=ccitt2     OPTIONSP=                      dotest1
-	make IMG=ccitt3     OPTIONSP=                      dotest1
-	make IMG=xvlogo    "OPTIONSP=-d 3"                 dotest1
-	make IMG=sandra     OPTIONSP=      OPTIONSJ=       dotest2g
-	make IMG=sandra     OPTIONSP=-b    OPTIONSJ=-b     dotest2g
-	make IMG=sandra     OPTIONSP=-q    OPTIONSJ=       dotest2g
-	make IMG=sandra    "OPTIONSP=-o 0" OPTIONSJ=       dotest2g
-	make IMG=sandra    "OPTIONSP=-o 2" OPTIONSJ=       dotest2g
-	make IMG=multi      OPTIONSP=      OPTIONSJ=       dotest2g
-	make IMG=multi      OPTIONSP=-b    OPTIONSJ=-b     dotest2g
-	make IMG=mx        "OPTIONSP=-q -s 3 -m 128"       dotest1
-	make IMG=mx        "OPTIONSP=-q -s 3 -m 128"       dotest2b
-	make IMG=mx        "OPTIONSP=-q -s 3 -m 128 -p 92" dotest2b
-	make IMG=mx        "OPTIONSP=-q -Y -1"             dotest2b
-	make IMG=mx        "OPTIONSP=-Y -1"                dotest2b
+	$(MAKE) IMG=ccitt1     OPTIONSP=                      dotest1
+	$(MAKE) IMG=ccitt2     OPTIONSP=                      dotest1
+	$(MAKE) IMG=ccitt3     OPTIONSP=                      dotest1
+	$(MAKE) IMG=xvlogo    "OPTIONSP=-d 3"                 dotest1
+	$(MAKE) IMG=sandra     OPTIONSP=      OPTIONSJ=       dotest2g
+	$(MAKE) IMG=sandra     OPTIONSP=-b    OPTIONSJ=-b     dotest2g
+	$(MAKE) IMG=sandra     OPTIONSP=-q    OPTIONSJ=       dotest2g
+	$(MAKE) IMG=sandra    "OPTIONSP=-o 0" OPTIONSJ=       dotest2g
+	$(MAKE) IMG=sandra    "OPTIONSP=-o 2" OPTIONSJ=       dotest2g
+	$(MAKE) IMG=multi      OPTIONSP=      OPTIONSJ=       dotest2g
+	$(MAKE) IMG=multi      OPTIONSP=-b    OPTIONSJ=-b     dotest2g
+	$(MAKE) IMG=mx        "OPTIONSP=-q -s 3 -m 128"       dotest1
+	$(MAKE) IMG=mx        "OPTIONSP=-q -s 3 -m 128"       dotest2b
+	$(MAKE) IMG=mx        "OPTIONSP=-q -s 3 -m 128 -p 92" dotest2b
+	$(MAKE) IMG=mx        "OPTIONSP=-q -Y -1"             dotest2b
+	$(MAKE) IMG=mx        "OPTIONSP=-Y -1"                dotest2b
 	rm -f test-*.jbg test-*.pbm test-*.pgm
 	./jbgtopbm ../examples/ccitt1.jbg | ./pbmtojbg > test-ccitt1.jbg
 	cmp ../examples/ccitt1.jbg test-ccitt1.jbg
@@ -96,24 +96,24 @@
 	cmp test-$(IMG).pgm ../examples/$(IMG).pgm
 
 test85: pbmtojbg jbgtopbm pbmtojbg85 jbgtopbm85 test-t82.pbm
-	make IMG=t82 "OPTIONSP=-p 0"      dotest85
-	make IMG=t82 "OPTIONSP=-p 8"      dotest85
-	make IMG=t82 "OPTIONSP=-p 8 -r"   dotest85b
-	make IMG=t82 "OPTIONSP=-p 64"     dotest85
-	make IMG=t82 "OPTIONSP=-p 72"     dotest85
-	make IMG=t82 "OPTIONSP=-s 2 -C c" dotest85
-	make IMG=t82 "OPTIONSP=-s 99999"  dotest85
-	make IMG=t82 "OPTIONSP=-Y 9999 0" dotest85
-	make IMG=t82 "OPTIONSP=-Y 1951 0" dotest85
-	make IMG=t82 "OPTIONSP=-Y -1 127" dotest85
-	make IMG=t82 "OPTIONSP=-Y -1 128" dotest85
-	make IMG=t82 "OPTIONSP=-Y -1 1919" dotest85
-	make IMG=t82 "OPTIONSP=-Y -1 1920" dotest85
-	make IMG=t82 "OPTIONSP=-Y -1 1949" dotest85
-	make IMG=t82 "OPTIONSP=-Y -1 1950" dotest85
-	make IMG=ccitt1 dotest85
-	make IMG=ccitt2 dotest85
-	make IMG=ccitt3 dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-p 0"      dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-p 8"      dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-p 8 -r"   dotest85b
+	$(MAKE) IMG=t82 "OPTIONSP=-p 64"     dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-p 72"     dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-s 2 -C c" dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-s 99999"  dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-Y 9999 0" dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-Y 1951 0" dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-Y -1 127" dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-Y -1 128" dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-Y -1 1919" dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-Y -1 1920" dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-Y -1 1949" dotest85
+	$(MAKE) IMG=t82 "OPTIONSP=-Y -1 1950" dotest85
+	$(MAKE) IMG=ccitt1 dotest85
+	$(MAKE) IMG=ccitt2 dotest85
+	$(MAKE) IMG=ccitt3 dotest85
 	rm -f test-*.jbg test-*.jbg85 test-*.pbm
 	@echo
 	@echo "The T.85 pbmtools have PASSED the functional tests. Good!"
@@ -147,7 +147,7 @@
 	./jbgtopbm $< $@
 
 test-t82.pbm:
-	make -C ../libjbig tstcodec
+	$(MAKE) -C ../libjbig tstcodec
 	../libjbig/tstcodec $@
 
 FOPT=-c 1000 -p 300000 -m 3